sql - 具有一个条件和多个结果的 SQL CASE

Question

我正在编写一个存储过程，它将字符串作为输入参数之一，然后检索结果。

我熟悉以下 SQLCASE格式。

CASE
  WHEN col1 in ('val1', 'val2', 'val3')
  THEN 'HELLO'    
  WHEN col1 in ('val4', 'val5', 'val6') 
  THEN 'WORLD'    
END AS col2

其他方式的查询应该是什么？

就像我给col2value as 一样'HELLO'，它应该返回所有col1包含的行'val1', 'val2', 'val3'

Answer 1

只需将其包装在另一个查询中...

SELECT *
FROM (
      SELECT CASE
             WHEN col1 in ('val1', 'val2', 'val3')
             THEN 'HELLO'    
             WHEN col1 in ('val4', 'val5', 'val6') 
             THEN 'WORLD'    
             END AS col2
...
     )t
WHERE t.col2 = 'HELLO'

Answer 2

你可以试试这个。

SELECT
   col1,
   CASE
   WHEN col1 in ('val1', 'val2', 'val3')
   THEN 'HELLO'    
   WHEN col1 in ('val4', 'val5', 'val6') 
   THEN 'WORLD'    
   END AS col2
FROM
   --wherever you are getting your data from...
WHERE
   col2 = :SEARCH

当您将 HELLO 传递给绑定变量时，它将返回如下所示的结果。

col1 col2
---- ----
val1 HELLO
val2 HELLO
val3 HELLO

如果你只想返回 col1，你可以做这样的事情

WITH SEARCH_RESULTS AS
(
   SELECT
      col1,
      CASE
      WHEN col1 in ('val1', 'val2', 'val3')
      THEN 'HELLO'    
      WHEN col1 in ('val4', 'val5', 'val6') 
      THEN 'WORLD'    
      END AS col2
   FROM
      --wherever you are getting your data from...
   WHERE
      col2 = :SEARCH
)

SELECT col1 FROM SEARCH_RESULTS

Answer 3

WHERE 1 = CASE
  WHEN (col2 = 'HELLO' and col1 in ('val1', 'val2', 'val3'))
    OR (col2 = 'WORLD' and col1 in ('val4', 'val5', 'val6'))
  THEN 1
  ELSE 0
  END

或者，更简单地说..

WHERE  (col2 = 'HELLO' and col1 in ('val1', 'val2', 'val3'))
    OR (col2 = 'WORLD' and col1 in ('val4', 'val5', 'val6'))

Answer 4

其中 (col2 = 'HELLO' and col1 in ('val1', 'val2', 'val3')) 或 (col2 = 'WORLD' and col1 in ('val4', 'val5', 'val6'))